A bit of supporting evidence.The sides of the frame-- the vertical "wall" below the edge of the walkway, to which (in post-1964 U25B and all later domestic GE hood units) the stanchions for the handrails are bolted-- are noticeably wider (top to bottom) on six axle U-series, Dash-7 series, and non-W C40-8 than they are on the C40-8W and C44-9W and AC44CW: this is a difference that can be seen easily, and doesn't require careful measurements on a photo!The frame sides on a Norfolk Southern "conventional cab" C40-9 are narrow, like those on wide-nose GE units.I think this supports the suggestion that the C40-9 was built on C44-9W-style frames, and not on the higher-deck frames of (non-W) C40-8. And that there would therefore be no problem fitting a standard GE wide-nose cab onto them.

Michael, I know you have very detailed drawings of many locomotive types. Do you have anything that would let you compare the "conventional" cab on a C40-9 to that on a C40-8?

Michael, I know you have very detailed drawings of many locomotive types. Do you have anything that would let you compare the "conventional" cab on a C40-9 to that on a C40-8?

Yep, I've measured both cabs from photos - and the cab itself appears the same between the Dash 8-40C and Dash 9-40C.

However, the Dash 9-40C does ride on the standard Dash-9/AC/ES frame, and all of the hood behind the cab is the same as the Dash 9-40CW (except for the absence of the A/C box on the left side). This frame is substantially thicker than the one on the Dash 8-40CW since the bottom frame rail is not nearly as high off the trucks, but the walkway height is only 1 inch higher than on the Dash 8-40CW (about 5' 11", or still 4 inches lower than the Dash 8-40C).

With regard to the cab and short hood, the standard cab itself is the same between the Dash 8-40C and Dash 9-40C, but it sits on a 5-inch higher sub-base on the Dash-9 in order to match the taller hood (making it the same overall height as the wide-nosed cab). To compensate, the nose is 5 inches taller than on the Dash-8.

As for the wide-nosed cab, it has all the same general dimensions from the Dash-8 up to the ES series.

What this all means is that the NS standard-cab Dash-9's rebuilt with AC motors and wide-nose cabs are extremely similar visually to a stock AC4400CW - because much of the frame and hood was already the same.

Michael-- Thank you very much for the detailed reply! … GE, I suspect, had decided at the time they introduced the Dash-9, that they would never again build a "standard" cab freight unit for North Ameerican service… but Norfolk Southern insisted (I wonder if some exasperated person in GE's engineering department asked "Ehy don't they ask for high short hoods, too?" (Grin!)). Putting a new sub-base under the lot cab was obviously an easier bit of engineering for GE than designing an all-new cab, or re-working the frame design from the C40-8 conventional cab unit to accommodate Dash-9 machinery!

Interestingly, the height from the cab sub-base to the cab roof is about the same on the standard and wide-nosed cabs, which means that the sub-base on the Dash 9-40C is the same height as on the W units (which I guess would further simplify the conversion). It appears that the extra height of the wide-nosed cab was not to create a taller interior, but to raise the short hood high enough to walk inside. The standard Dash-8 nose is only about 5 1/2 feet high - and that's on the outside. The W nose added almost a foot to that.

Compared to Dash 7 and standard-cab Dash 8 units, EMD units had shorter frames (and therefore taller cabs and noses). As a result, there is only about an inch difference in height between the EMD standard and wide-nosed cab roofs, and no changes were made to the frame height between cab types.

I've been hearing that the Dash 8.5 program has been canceled and that NS is now in the process of scrapping their remaining unrebuilt Dash 8s. Lots of speculation on why this is happening but I haven't heard anything official.

NS will be completing a total of 14 units, 8500-8513, before the program is at least temporarily stopped as Roanoke transitions to AC44C6M production. The future of the program has not been officially announced but doesn't look good. NS has been scrapping Dash 8-40Cs. Originally the intention was to have the same amount of Dash 8.5s as original C40-8s, but it is possible that some of the conversions were intended to be C40-8Ws.